Thumbtacks and pushpins (a.k.a. map pins) are widely used to hang objects, including planar and non-planar objects, onto suitable support surfaces. Planar objects include various types of paper items, such as documents, posters, photographs, cardstock, paper labels, paintings and the like. Other planar objects include textile items such as cloth samples, cloth labels and the like. Certain non-planar objects are often hung by thumbtacks and pushpins, including various objects on hangers, lightweight toys, clothing items and accessories, various samples, protective cases housing other objects and the like. Indeed, the list of planar and non-planar objects goes on. Suitable support surfaces include foamboard, corkboard, particleboard, drywall, plaster and like surfaces puncturable by thumbtacks and pushpins. For example, support surfaces such as bulletin boards and cubicle walls (typically fabric-coated foamboard) are often used in combination with thumbtacks and pushpins to affix objects to such surfaces.
Conventional thumbtacks and pushpins consist of a head and a pin. By applying a lower pressure across the head of a thumbtack or pushpin positioned against a surface, a relatively higher pressure results at the tip of the pin. If the surface is a suitable support surface, then the pin will puncture the surface. When a puncturable object is placed between the tip and the support surface, the object is also punctured. The head of the thumbtack or pushpin acts as a stopper if the pin is pressed towards full engagement with or through the support surface. When this occurs, a portion of the punctured object is pressed between the head and the support surface.
Objects held as such are often prone to tearing stresses at the point of puncture due to a loose or loosening hold, or even despite a firm hold, depending on the properties (weight, material, shape, etc.), of the held object. To avoid puncturing the object as is often desirable, the pin is often made to puncture the support surface outside the bounds of an object, and a portion of the object can be pressed between the head and the support surface. This method is often used to trap an edge of a planar object between the head and the support surface. As opposed to puncturing the object, this method is more prone to retaining failure. Nevertheless, it has been employed to avoid puncturing an object and to avoid later tearing at a puncture point.
T-pins are another type of device often used to hang objects. Moreover, various clips are used for fastening one object to another. A variety of specialty hanging clips that are designed to be affixed or otherwise associated with a support surface for holding objects are also known.